1. Field of the Invention
Air freshening devices.
2. Background Art
Devices designed to dispense fragrance materials into the ambient air to impart a desirable and pleasant fragrance are well known in the art. Such devices, commonly known as air fresheners or room deodorizers, are commercially available in a variety of forms. Some of these devices are quite simple while others, which involve mechanical systems, are more complex.
Ideally, the device should be as simple as possible, require little or no maintenance and should perform in a manner that allows the fragrance material to be dispensed at a steady and controlled rate into the designated area while maintaining its odor integrity over the life span of the device. Unfortunately, nearly all of the relatively simple non-aerosol devices that are commercially available suffer from the same limitation. The odor becomes distorted over the life span of the device due to the fact that the more volatile components are removed first, leaving the less volatile components behind. This change of the composition with time eventually results in a weakening of the intensity of the fragrance since the less volatile components evaporate more slowly. It is these two problems, i.e., the weakening of intensity and distortion over the lifetime of the fragrance material, that have occupied much of the attention of those who seek to devise better air freshener devices.
Practically all devices which depend on evaporation from a surface suffer from the shortcomings mentioned above. In most of these devices, a wick, gel or porous surface simply provides a greater surface area from which the fragrance material can evaporate more quickly, but fractionation still occurs, as it would from the surface of the liquid itself, resulting in an initial burst of fragrance followed by a period of lower intensity once the more volatile components have evaporated. Due to this fractionation and perhaps a clogging of the wick and/or other evaporative surfaces, the fragrance becomes distorted and its intensity weakens perceptibly.
Various methods have been tried in an effort to overcome such problems and some have met with limited success. For example, surface active agents have been used to control the release of the fragrance, but these non-volatile substances often clog up delivery devices such as wicks and the use of such materials has not provided the desired degree of linearity of evaporation. Another method reported to be successful in minimizing distortion, involved creating a fragrance material using only components having similar volatility so that they would all evaporate at the same rate. The use of non-volatile solvents such as high boiling low-parrafin hydrocarbons has also been reported to slow down the initial burst of fragrance caused by the more volatile components. (See U.S. Pat. Nos. 2,529,536; 4,250,165; 4,304,688; 4,320,873; 4,323,193.)
The most common devices are those which, as stated above, depend on an evaporative surface and a delivery system for transferring the fragrance material to that evaporative surface. Despite the fact that most of these devices suffer from the limitation that there is distortion and a weakening of the fragrance with time, they are still very widely used inasmuch as they are simple and do provide a fragrance over a long period of time, an advantage they have over aerosol-type systems. Aerosol-type systems, while they do maintain fragrance integrity over their useful life, are useful only while they are being sprayed and, unless constantly sprayed, they lose their effectiveness in a few minutes. Each spray of the aerosol does, however, emit the same composition so that continued use does not result in distortion or decreased odor intensity. It simply is not practical, however, to use an aerosol, as a continous dispenser of fragrances.
Mechanical devices have been developed to overcome the limitations mentioned above including the problems of non-linear delivery and distortion of the air freshening material. These systems are devices which introduce a premeasured amount of the fragrance material into the ambient air at regularly timed intervals. Such devices are either electrically or battery operated. The material may be dispensed as an aerosol by a mechanical system or the device may employ fans to dispense a premeasured amount of liquid. These devices are usually complex and designed for commerical rather than home use.
None of the prior art devices fully satisfies the need for an air freshening system which is simple in design and yet can deliver an air freshening material to the ambient air over a long period of time without change in the rate of delivery, or in the odor character of the fragrance, during the life of the device.